![[BACK]](/icons/back.gif){kind=icon}
Return to forwback.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / less|
Return to forwback.c CVS log | Up to [local] / src / usr.bin / less |
1.1 etheisen 1: /*
1.7 ! shadchin 2: * Copyright (C) 1984-2011 Mark Nudelman
1.1 etheisen 3: *
1.5 millert 4: * You may distribute under the terms of either the GNU General Public
5: * License or the Less License, as specified in the README file.
1.1 etheisen 6: *
1.5 millert 7: * For more information about less, or for information on how to
8: * contact the author, see the README file.
1.1 etheisen 9: */
10:
11:
12: /*
13: * Primitives for displaying the file on the screen,
14: * scrolling either forward or backward.
15: */
16:
17: #include "less.h"
18: #include "position.h"
19:
20: public int screen_trashed;
21: public int squished;
1.5 millert 22: public int no_back_scroll = 0;
1.7 ! shadchin 23: public int forw_prompt;
1.1 etheisen 24:
25: extern int sigs;
26: extern int top_scroll;
27: extern int quiet;
28: extern int sc_width, sc_height;
29: extern int plusoption;
30: extern int forw_scroll;
31: extern int back_scroll;
32: extern int ignore_eoi;
1.5 millert 33: extern int clear_bg;
34: extern int final_attr;
1.7 ! shadchin 35: extern int oldbot;
1.1 etheisen 36: #if TAGS
37: extern char *tagoption;
38: #endif
39:
40: /*
41: * Sound the bell to indicate user is trying to move past end of file.
42: */
43: static void
44: eof_bell()
45: {
46: if (quiet == NOT_QUIET)
47: bell();
48: else
49: vbell();
50: }
51:
52: /*
1.7 ! shadchin 53: * Check to see if the end of file is currently displayed.
1.1 etheisen 54: */
1.7 ! shadchin 55: public int
! 56: eof_displayed()
1.1 etheisen 57: {
58: POSITION pos;
59:
60: if (ignore_eoi)
1.7 ! shadchin 61: return (0);
! 62:
! 63: if (ch_length() == NULL_POSITION)
! 64: /*
! 65: * If the file length is not known,
! 66: * we can't possibly be displaying EOF.
! 67: */
! 68: return (0);
! 69:
1.1 etheisen 70: /*
71: * If the bottom line is empty, we are at EOF.
72: * If the bottom line ends at the file length,
73: * we must be just at EOF.
74: */
75: pos = position(BOTTOM_PLUS_ONE);
1.7 ! shadchin 76: return (pos == NULL_POSITION || pos == ch_length());
! 77: }
! 78:
! 79: /*
! 80: * Check to see if the entire file is currently displayed.
! 81: */
! 82: public int
! 83: entire_file_displayed()
! 84: {
! 85: POSITION pos;
! 86:
! 87: /* Make sure last line of file is displayed. */
! 88: if (!eof_displayed())
! 89: return (0);
! 90:
! 91: /* Make sure first line of file is displayed. */
! 92: pos = position(0);
! 93: return (pos == NULL_POSITION || pos == 0);
1.1 etheisen 94: }
95:
96: /*
97: * If the screen is "squished", repaint it.
98: * "Squished" means the first displayed line is not at the top
99: * of the screen; this can happen when we display a short file
100: * for the first time.
101: */
1.7 ! shadchin 102: public void
1.1 etheisen 103: squish_check()
104: {
105: if (!squished)
106: return;
107: squished = 0;
108: repaint();
109: }
110:
111: /*
112: * Display n lines, scrolling forward,
113: * starting at position pos in the input file.
114: * "force" means display the n lines even if we hit end of file.
115: * "only_last" means display only the last screenful if n > screen size.
116: * "nblank" is the number of blank lines to draw before the first
117: * real line. If nblank > 0, the pos must be NULL_POSITION.
118: * The first real line after the blanks will start at ch_zero().
119: */
120: public void
121: forw(n, pos, force, only_last, nblank)
1.5 millert 122: register int n;
1.1 etheisen 123: POSITION pos;
124: int force;
125: int only_last;
126: int nblank;
127: {
128: int eof = 0;
129: int nlines = 0;
130: int do_repaint;
131: static int first_time = 1;
132:
133: squish_check();
134:
135: /*
136: * do_repaint tells us not to display anything till the end,
137: * then just repaint the entire screen.
138: * We repaint if we are supposed to display only the last
139: * screenful and the request is for more than a screenful.
140: * Also if the request exceeds the forward scroll limit
141: * (but not if the request is for exactly a screenful, since
142: * repainting itself involves scrolling forward a screenful).
143: */
144: do_repaint = (only_last && n > sc_height-1) ||
145: (forw_scroll >= 0 && n > forw_scroll && n != sc_height-1);
146:
147: if (!do_repaint)
148: {
149: if (top_scroll && n >= sc_height - 1 && pos != ch_length())
150: {
151: /*
152: * Start a new screen.
153: * {{ This is not really desirable if we happen
154: * to hit eof in the middle of this screen,
155: * but we don't yet know if that will happen. }}
156: */
1.5 millert 157: pos_clear();
158: add_forw_pos(pos);
159: force = 1;
1.7 ! shadchin 160: clear();
1.1 etheisen 161: home();
162: }
163:
164: if (pos != position(BOTTOM_PLUS_ONE) || empty_screen())
165: {
166: /*
167: * This is not contiguous with what is
168: * currently displayed. Clear the screen image
169: * (position table) and start a new screen.
170: */
171: pos_clear();
172: add_forw_pos(pos);
173: force = 1;
174: if (top_scroll)
175: {
1.7 ! shadchin 176: clear();
1.1 etheisen 177: home();
178: } else if (!first_time)
179: {
180: putstr("...skipping...\n");
181: }
182: }
183: }
184:
185: while (--n >= 0)
186: {
187: /*
188: * Read the next line of input.
189: */
190: if (nblank > 0)
191: {
192: /*
193: * Still drawing blanks; don't get a line
194: * from the file yet.
195: * If this is the last blank line, get ready to
196: * read a line starting at ch_zero() next time.
197: */
198: if (--nblank == 0)
199: pos = ch_zero();
200: } else
201: {
202: /*
203: * Get the next line from the file.
204: */
205: pos = forw_line(pos);
206: if (pos == NULL_POSITION)
207: {
208: /*
209: * End of file: stop here unless the top line
210: * is still empty, or "force" is true.
1.5 millert 211: * Even if force is true, stop when the last
212: * line in the file reaches the top of screen.
1.1 etheisen 213: */
214: eof = 1;
215: if (!force && position(TOP) != NULL_POSITION)
216: break;
1.5 millert 217: if (!empty_lines(0, 0) &&
218: !empty_lines(1, 1) &&
219: empty_lines(2, sc_height-1))
220: break;
1.1 etheisen 221: }
222: }
223: /*
224: * Add the position of the next line to the position table.
225: * Display the current line on the screen.
226: */
227: add_forw_pos(pos);
228: nlines++;
229: if (do_repaint)
230: continue;
231: /*
232: * If this is the first screen displayed and
233: * we hit an early EOF (i.e. before the requested
234: * number of lines), we "squish" the display down
235: * at the bottom of the screen.
236: * But don't do this if a + option or a -t option
237: * was given. These options can cause us to
238: * start the display after the beginning of the file,
239: * and it is not appropriate to squish in that case.
240: */
241: if (first_time && pos == NULL_POSITION && !top_scroll &&
242: #if TAGS
243: tagoption == NULL &&
244: #endif
245: !plusoption)
246: {
247: squished = 1;
248: continue;
249: }
250: put_line();
1.7 ! shadchin 251: #if 0
! 252: /* {{
! 253: * Can't call clear_eol here. The cursor might be at end of line
! 254: * on an ignaw terminal, so clear_eol would clear the last char
! 255: * of the current line instead of all of the next line.
! 256: * If we really need to do this on clear_bg terminals, we need
! 257: * to find a better way.
! 258: * }}
! 259: */
! 260: if (clear_bg && apply_at_specials(final_attr) != AT_NORMAL)
1.5 millert 261: {
262: /*
263: * Writing the last character on the last line
264: * of the display may have scrolled the screen.
265: * If we were in standout mode, clear_bg terminals
266: * will fill the new line with the standout color.
267: * Now we're in normal mode again, so clear the line.
268: */
269: clear_eol();
270: }
1.7 ! shadchin 271: #endif
! 272: forw_prompt = 1;
1.1 etheisen 273: }
274:
275: if (nlines == 0)
276: eof_bell();
277: else if (do_repaint)
278: repaint();
279: first_time = 0;
280: (void) currline(BOTTOM);
281: }
282:
283: /*
284: * Display n lines, scrolling backward.
285: */
286: public void
287: back(n, pos, force, only_last)
1.5 millert 288: register int n;
1.1 etheisen 289: POSITION pos;
290: int force;
291: int only_last;
292: {
293: int nlines = 0;
294: int do_repaint;
295:
296: squish_check();
297: do_repaint = (n > get_back_scroll() || (only_last && n > sc_height-1));
298: while (--n >= 0)
299: {
300: /*
301: * Get the previous line of input.
302: */
303: pos = back_line(pos);
304: if (pos == NULL_POSITION)
305: {
306: /*
307: * Beginning of file: stop here unless "force" is true.
308: */
309: if (!force)
310: break;
311: }
312: /*
313: * Add the position of the previous line to the position table.
314: * Display the line on the screen.
315: */
316: add_back_pos(pos);
317: nlines++;
318: if (!do_repaint)
319: {
320: home();
321: add_line();
322: put_line();
323: }
324: }
325:
326: if (nlines == 0)
327: eof_bell();
328: else if (do_repaint)
329: repaint();
1.7 ! shadchin 330: else if (!oldbot)
! 331: lower_left();
1.1 etheisen 332: (void) currline(BOTTOM);
333: }
334:
335: /*
336: * Display n more lines, forward.
337: * Start just after the line currently displayed at the bottom of the screen.
338: */
339: public void
340: forward(n, force, only_last)
341: int n;
342: int force;
343: int only_last;
344: {
345: POSITION pos;
346:
1.7 ! shadchin 347: if (get_quit_at_eof() && eof_displayed() && !(ch_getflags() & CH_HELPFILE))
1.1 etheisen 348: {
349: /*
350: * If the -e flag is set and we're trying to go
351: * forward from end-of-file, go on to the next file.
352: */
353: if (edit_next(1))
354: quit(QUIT_OK);
355: return;
356: }
357:
358: pos = position(BOTTOM_PLUS_ONE);
359: if (pos == NULL_POSITION && (!force || empty_lines(2, sc_height-1)))
360: {
361: if (ignore_eoi)
362: {
363: /*
364: * ignore_eoi is to support A_F_FOREVER.
365: * Back up until there is a line at the bottom
366: * of the screen.
367: */
368: if (empty_screen())
369: pos = ch_zero();
370: else
371: {
372: do
373: {
374: back(1, position(TOP), 1, 0);
375: pos = position(BOTTOM_PLUS_ONE);
376: } while (pos == NULL_POSITION);
377: }
1.5 millert 378: } else
379: {
1.1 etheisen 380: eof_bell();
381: return;
382: }
383: }
384: forw(n, pos, force, only_last, 0);
385: }
386:
387: /*
388: * Display n more lines, backward.
389: * Start just before the line currently displayed at the top of the screen.
390: */
391: public void
392: backward(n, force, only_last)
393: int n;
394: int force;
395: int only_last;
396: {
397: POSITION pos;
398:
399: pos = position(TOP);
400: if (pos == NULL_POSITION && (!force || position(BOTTOM) == 0))
401: {
402: eof_bell();
403: return;
404: }
405: back(n, pos, force, only_last);
406: }
407:
408: /*
409: * Get the backwards scroll limit.
410: * Must call this function instead of just using the value of
411: * back_scroll, because the default case depends on sc_height and
412: * top_scroll, as well as back_scroll.
413: */
414: public int
415: get_back_scroll()
416: {
1.5 millert 417: if (no_back_scroll)
418: return (0);
1.1 etheisen 419: if (back_scroll >= 0)
420: return (back_scroll);
421: if (top_scroll)
422: return (sc_height - 2);
423: return (10000); /* infinity */
424: }